Carbon Dioxide Capture by a Hydrothermally Synthesized Water-Resistant Zinc-Oxalate-Aminotriazolate Framework

Selective capture of carbon dioxide (CO₂) from flue gas employing physisorbents represents an appealing approach owing to its potentially low energy penalty and cost-effectiveness. Microporous metal-organic frameworks (MOFs), characterized by their highly customizable pore structure and functionality, offer significant promise in this field. However, challenges such as thermal/moisture resistance, green/scalable synthesis, and adsorption durability remain unresolved. Here, we demonstrate the effective capture of CO₂ from flue gas using a microporous zinc-oxalate-aminotriazolate (Zn-OX-ATZ) framework material. Zn-OX-ATZ is synthesized directly in water from zinc oxalate and 3-amino-1,2,4-trazole, achieving high atom economy. It displays a CO₂ adsorption capacity of 2.29 mmol g^-1 at 318 K and 0.15 bar, with a CO₂/N₂ selectivity exceeding 78000. Notably, its structural integrity and CO₂ adsorption capability are fully maintained under highly humid conditions, as evidenced by over 50 adsorption-desorption cycles. The practical applicability of Zn-OX-ATZ for industrial CO₂ capture has been experimentally validated using simulated flue gas at the kilogram scale. Additionally, we have elucidated the underlying mechanism and adsorption domains of CO₂ in the presence of H₂O at the molecular level through a combination of gas-loaded single-crystal X-ray diffraction, in situ infrared spectroscopy, and ab initio modeling. This study presents a durable physisorbent for CO₂ capture, characterized by well-balanced adsorption capacity and selectivity, high water stability and resistance, green preparation, and, therefore, strong practical applicability.